阅读说明：本技术 基于三维电催化导电膜蒸馏的放射性废水处置系统 (Radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation ) 是由 刘畅 杨文澜 纪荣平 程浩淼 蔡森 于 2021-07-21 设计创作，主要内容包括：本发明公开了基于三维电催化导电膜蒸馏的放射性废水处置系统,包括管路依次连接的用于放置放射性废液的废液贮存池、用于将废液中的放射性元素与化学沉淀剂进行沉淀反应的沉淀池、用于对沉淀池预处理后的废液进行加热处理的膜蒸馏加热池、用于将废液中放射性元素絮凝沉淀排出及拦截金属离子和放射性物质的三维电催化导电膜蒸馏反应池、用于存储渗透液的清水池；还包括为沉淀池提供酸性条件的pH调节池。本发明利用化学沉淀法预处理放射性废水,再经过三维电催化导电膜蒸馏反应池进一步氧化、絮凝沉淀、拦截去除废液中的放射性元素和金属离子,出水水质高度纯化,实现放射性废水的高效减量化与无害化处置,具有切实可行的实用价值和广泛的应用前景。(The invention discloses a radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation, which comprises a waste liquid storage pool, a sedimentation pool, a membrane distillation heating pool, a three-dimensional electro-catalytic conductive membrane distillation reaction pool and a clear water pool, wherein the waste liquid storage pool is used for placing radioactive waste liquid, the sedimentation pool is used for carrying out precipitation reaction on radioactive elements in the waste liquid and a chemical precipitator, the membrane distillation heating pool is used for heating the waste liquid pretreated by the sedimentation pool, the three-dimensional electro-catalytic conductive membrane distillation reaction pool is used for discharging the radioactive elements in the waste liquid through flocculation and precipitation and intercepting metal ions and radioactive substances, and the clear water pool is used for storing penetrating fluid; also comprises a pH adjusting tank for providing acidic conditions for the sedimentation tank. According to the invention, the radioactive wastewater is pretreated by using a chemical precipitation method, and then is further oxidized, flocculated and precipitated, and intercepted and removed of radioactive elements and metal ions in the waste liquid by using the three-dimensional electro-catalytic conductive membrane distillation reaction tank, so that the effluent quality is highly purified, the efficient reduction and harmless treatment of the radioactive wastewater are realized, and the method has practical and feasible practical values and wide application prospects.)

1. The radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation is characterized by comprising a waste liquid storage pool, a sedimentation pool, a membrane distillation heating pool, a three-dimensional electro-catalytic conductive membrane distillation reaction pool and a clear water pool, wherein the waste liquid storage pool is used for placing radioactive waste liquid, the sedimentation pool is used for carrying out precipitation reaction on radioactive elements in the waste liquid and a chemical precipitator, the membrane distillation heating pool is used for heating the waste liquid pretreated by the sedimentation pool, the three-dimensional electro-catalytic conductive membrane distillation reaction pool is used for discharging the radioactive elements in the waste liquid through flocculation and precipitation and intercepting metal ions and radioactive substances, and the clear water pool is used for storing penetrating fluid; also comprises a pH adjusting tank for providing acidic conditions for the sedimentation tank.

2. The radioactive waste water treatment system based on three-dimensional electrocatalytic conductive membrane distillation as claimed in claim 1, wherein an electrocatalytic oxidation anode, an iron-carbon microelectrolytic filler and a conductive distillation membrane are sequentially arranged in a shell of the three-dimensional electrocatalytic conductive membrane distillation reaction tank, hot waste liquid in the membrane distillation heating tank is conveyed into the three-dimensional electrocatalytic conductive membrane distillation reaction tank through a fourth sewage pump, and the waste liquid is returned to the sedimentation tank through the first circulating pump; and the penetrating fluid outlet water of the three-dimensional electrocatalytic conductive membrane distillation reaction tank is conveyed to a condenser through a second circulating pump for cooling and condensing treatment, and the condensed penetrating fluid is conveyed to a clean water tank.

3. The radioactive waste water treatment system based on distillation of a three-dimensional electrocatalytic conductive film as set forth in claim 2, wherein the temperature of the condenser is controlled at 15 ± 5 ℃; a liquid level controller is arranged in the clean water tank, and clean water exceeding a set water level in the clean water tank is conveyed to a clean water storage tank through a cold side water pump to be stored for later use; and a water outlet quality control system is arranged in the clean water tank and is connected with a computer to control the regeneration of the iron-carbon micro-electrolysis filler in the three-dimensional electro-catalytic conductive membrane distillation reaction tank, the membrane cleaning of the conductive distillation membrane and the membrane replacement.

4. The radioactive waste water treatment system based on distillation of three-dimensional electrocatalytic conductive film according to claim 2 or 3, wherein the iron-carbon micro-electrolysis filler is carbon nanotube modified iron-carbon micro-electrolysis filler, comprising the following steps:

step 1, pretreatment of a preparation material: putting magnet powder, coconut shell charcoal powder and carbon nanotube powder into 1.5g/LNaOH solution, mixing for 20-30min, taking out, cleaning with ultrapure water, soaking in dilute sulfuric acid solution for 20min, taking out, cleaning, and drying in a 120 deg.C drying oven for 10-12 h;

step 2, preparing filler slurry: weighing 60g of pretreated magnet powder, 30g of coconut shell charcoal powder and 30g of carbon nanotube powder, weighing 5g of bentonite as an adhesive, weighing 5-6g of ammonium oxalate as a pore-forming agent, weighing 3.5g of nickel powder as an additive, placing the mixture into 300mL of ultrapure water, and stirring the mixture for 1-2 hours at 60 ℃ in a water bath to obtain filler slurry;

and 3, granulating the filler: carrying out artificial granulation on the prepared filler slurry, setting the particle size to be 1-2cm, and drying the filler slurry for 3-4h at 150 ℃ in a vacuum drying oven after the granulation is finished;

and 4, insulating treatment of filler particles: performing insulation treatment on the granulated filler particles by using polyimide, and coating a polyimide insulation layer on the surfaces of the filler particles;

step 5, roasting and curing: and (3) placing the filler particles subjected to insulation treatment in a crucible, wrapping the filler particles by using tin foil paper, placing the filler particles in a muffle furnace for roasting at the high temperature of 200 ℃ for 6 hours, and placing the muffle furnace at room temperature for cooling to obtain the self-made carbon nano tube modified iron-carbon micro-electrolysis filler.

5. The radioactive waste water treatment system based on distillation of three-dimensional electrocatalytic conductive membrane according to claim 2 or 3, wherein the conductive distillation membrane employs TiO₂A/CNTs distillation membrane, comprising the steps of:

step 1, pretreating carbon nanotube CNTs powder: weighing 40-50g of CNTs powder, placing the CNTs powder in a beaker, adding 250mL of 200-250mL of deionized water, placing the beaker in a constant-temperature water bath kettle, heating the beaker for 2-3h at 100 ℃, placing the beaker in a room-temperature environment, cooling the beaker, repeatedly washing the beaker with deionized water to remove impurities in the CNTs slurry, performing suction filtration on the slurry by using a vacuum pump to obtain pure CNTs powder, and placing the CNTs powder in a muffle furnace, heating and activating the CNTs powder for 10-12h at 200 ℃;

step 2, preparing the nano titanium dioxide/carbon nano tube catalyst material: weighing 60-70g of tetrabutyl titanate and 20-30g of CNTs powder, adding 100-150mL of anhydrous ethanol, mixing, and magnetically stirring for 50min to form a mixed solution A; weighing 20mL of absolute ethyl alcohol, 50mL of deionized water and 30mL of concentrated nitric acid, mixing, and magnetically stirring for 50min to form a mixed solution B; slowly dropwise adding the solution B into the solution A, standing for 3-6h to form a gel substance, drying in an oven at 120 deg.C for 12h to obtain black gray powdery particulate matter, grinding the particulate matter into powder with a mortar, and calcining at 600 deg.C in a muffle furnace for 3h to obtain the final productTo obtain TiO₂CNTs catalyst powder;

step 3, TiO₂Preparation of a/CNTs distillation membrane: weighing 30-40g of TiO₂Adding the/CNTs catalyst powder into 200mL of ethanol solution, fully mixing, and adding 3-4g of carbon nanotube dispersing agent; after ultrasonic dispersion for 20-30min, adding 5 mass percent of cross-linking agent polyvinylidene fluoride (PVDF), placing in a water bath environment at 65 ℃ for water bath stirring for 1-2h, and obtaining TiO after vacuum deaeration for 20-30min₂CNTs catalyst slurry; adding TiO into the mixture₂Transferring the/CNTs catalyst coating slurry into a material pouring device, taking polytetrafluoroethylene PTFE as a hydrophobic base membrane, placing the hydrophobic base membrane on a coating machine, setting the thickness of a conductive coating to be 200-400 mu m, and using the coating machine to coat TiO₂/CNTs catalyst coating slurry is evenly coated on a PTFE hydrophobic surface, is kept stand and cured for 25min at room temperature and then is placed in a vacuum drying oven for drying for 48h at the temperature of 60-65 ℃, and then TiO is prepared₂/CNTs distillation membrane.

6. The radioactive wastewater treatment system based on distillation of a three-dimensional electrocatalytic conductive film according to claim 2, wherein the electrocatalytic anode is an iron-aluminum electrode.

7. The radioactive waste water treatment system based on distillation of a three-dimensional electrocatalytic conductive membrane according to claim 5, wherein the conductive distillation membrane has a membrane pore size of 0.1-0.4 μm.

8. The radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation as claimed in claim 1, wherein a mud scraper and a mud discharge pipe are arranged at the bottom of the sedimentation tank, the mud scraper is used for periodically scraping chemical sludge deposited at the bottom of the sedimentation tank, the chemical sludge is transported to the outside of the sedimentation tank through the mud discharge pipe and a mud discharge pump, the mud discharge period is set to 24h, and the chemical sludge discharged from the sedimentation tank is subjected to freezing, melting and vacuum filtration treatment processes for dehydration treatment and then is solidified by using cement;

a pH on-line monitoring system is arranged in the sedimentation tank and is used for controlling the extraction of a pH adjusting buffer solution in the pH adjusting tank and the addition of the pH adjusting buffer solution into the sedimentation tank so as to adjust the pH value of wastewater in the sedimentation tank;

the sedimentation tank is internally provided with a micropore aeration device, the micropore aeration device is used for full contact reaction between a chemical precipitator in the sedimentation tank and radioactive elements in waste liquid, the aeration intensity of the micropore aeration device is controlled by an air pump, a rotor flow meter monitors the aeration quantity value in real time, the aeration period is controlled by a computer, the aeration period is set to 10 hours, and the single aeration time is set to 30-40 min;

the medicine adding barrel is communicated with the interior of the sedimentation tank through a second feeding pump, the medicine adding barrel provides chemical precipitation medicine for the sedimentation tank,

the temperature of the sedimentation tank is controlled at 35 +/-5 ℃, the pH value is set to be 2-5, and the retention time of the sedimentation tank is 1-2 h.

9. The radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation as claimed in claim 8, wherein the dosing barrel is used for storing a chemical precipitation medicament prepared by mixing a copper ferrocyanide precipitator and a zinc potassium ferrocyanide adsorbent in proportion, the medicament in the dosing barrel is periodically dosed into the sedimentation tank through a second dosing pump, and the dosing period and the dosing amount of the medicament are controlled by the computer, and the dosing period is set to 10 hours.

10. The radioactive waste water treatment system based on three-dimensional electrocatalytic conductive membrane distillation as claimed in claim 1, wherein a heat collector heats the membrane distillation heating tank, the heat collector is connected with a solar energy absorption device providing heat energy, a temperature sensor is arranged in the membrane distillation heating tank, and the water temperature is controlled to be 65 ± 5 ℃.

Technical Field

The invention relates to the field of radioactive wastewater treatment, in particular to a radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation.

Background

Radioactive wastewater refers to various wastewater discharged in nuclear power plants, nuclear fuel pretreatment, spent fuel aftertreatment and radioisotope application processes, and the types, concentrations, acidity, other chemical components and the like of radioactive nuclides contained in different wastewater are greatly different. Radioactive waste water, after entering the environment, causes water and soil pollution and may enter the human body through various routes, causing harm to the environment and human beings.

At present, methods for treating radioactive wastewater generated by a nuclear power plant mainly include a chemical precipitation method, an ion exchange method, an evaporation concentration method, a membrane separation method, an adsorption method, and the like.

The chemical precipitation method mainly converts radioactive elements into insoluble precipitates such as hydroxides, carbonates, phosphates and the like and transfers and concentrates the insoluble precipitates into sludge, and is suitable for low-level wastewater with low purification requirements. However, the method has high requirement on the pH value of the wastewater in the treatment process, the treatment effect is obviously influenced by impurities contained in the wastewater, the quality of the radioactive sludge generated after treatment is large (usually 1-5% of the original water quantity), and secondary pollution is easily caused in subsequent dehydration reduction. In addition, when the formed radioactive sludge is immobilized by cement, the mechanical properties of the cement are easily damaged by the radioactive sludge, so that the immobilization effect is reduced, and secondary pollution is easily caused.

The ion exchange method is to exchange radioactive elements existing in an ion state in the wastewater to a polymer net rack of an ion exchanger for enrichment and concentration, although the removal rate is high, the operation is relatively complex, the operation cost is high, in addition, the ion exchanger needs to be frequently regenerated when the wastewater with high salt content is treated, and the treatment of the radioactive ion exchanger formed after the treatment at present also has certain difficulty.

The evaporation concentration method is to evaporate and condense water by heating so as to separate the water from the radioactive elements which are difficult to volatilize, and although the decontamination factor and the concentration factor are high, the energy consumption is high and the operation cost is high.

The membrane separation method is to separate and concentrate radioactive elements by means of a selective permeable membrane and taking pressure difference, temperature difference or potential difference as power, and the like, has good purification effect, but has higher construction and operation cost, and does not realize large-scale industrial application at present.

The adsorption method is to transfer radioactive elements to a solid phase by using an adsorbent for enrichment and concentration, and commonly used adsorbents include activated carbon, zeolite, montmorillonite and the like, but the adsorbents are greatly influenced by the pH value of wastewater, the adsorption effect is unstable, the solidification effect of the formed radioactive adsorbent in immobilization treatment is not good, and the radioactive elements are easy to release to form secondary pollution.

The electrocatalytic oxidation technology is to utilize metal oxide electrode with catalytic performance to produce hydroxyl radical or other free radical and radical with strong oxidation capacity to attack organic pollutant in solution and decompose the organic pollutant into harmless H₂O and CO₂Meanwhile, in the electrocatalytic oxidation technology process, iron, aluminum and other ions are generated by an electrode, and are developed into various hydroxyl complexes, polynuclear hydroxyl complexes or hydroxides through a series of hydrolysis, polymerization and ferrous oxidation processes, so that radioactive elements in the wastewater are coagulated, precipitated and separated. In order to further improve the mass transfer process of the traditional two-dimensional electrode system, a three-dimensional electrode system is proposed by scholars, namely, a large amount of composite particles (two ends of the particles can generate oxygen reduction reaction to form a large amount of microelectrodes) are filled between the two-dimensional electrode system, so that a third electrode is formed, the effective reaction area of the electrode is increased, and the reaction efficiency of electrocatalytic oxidation is improved. However, when the filler is made of materials with low impedance such as metal, activated carbon, graphite, etc. as the particle electrodes, the insulating particles must be added and mixed with the particle electrodes according to a certain volume ratio or mass ratio to form the composite filler, so as to reduce the short-circuit current between the particle electrodes, increase the reaction current, and improve the repolarization rate of the particle electrodes in the filler, thereby improving the current efficiency. In order to solve the problem, some researchers attempt to reduce the short-circuit current and improve the processing capacity and the processing effect of the three-dimensional electrode reactor by coating a cellulose acetate membrane on the surface of activated carbon particles as insulating particles. However, cellulose acetate is soluble in a wide variety of common solvents, not only inAniline, phenol, dichloromethane, tetrachloroethane, etc. are easily dissolved in solvents, and also dissolved in some mixed solvents (such as acetone and ethanol, and methane chloride and ethanol). Cellulose acetate has poor chemical thermal stability and compaction property, is easy to degrade and can be hydrolyzed under acid or alkaline conditions; in addition, the cellulose acetate film is not firmly combined with carriers such as activated carbon and the like, and is easy to fall off, thereby losing the effect. Therefore, the insulating particles prepared from the cellulose acetate coated activated carbon not only have short service life, but also have greatly limited application range. For the three-dimensional electrode reactor, the physical and chemical properties, mechanical properties, electrical properties, corrosion resistance, the degree of combination with a carrier and the like of the insulating particle surface coating material are key factors influencing the electrocatalytic oxidation effect of the three-dimensional electrode reactor.

The membrane distillation technology is a novel membrane separation technology combining membrane separation and distillation technology, a hydrophobic microporous filter membrane is used as a medium, under the action of steam pressure difference on two sides of the membrane, moisture in feed liquid penetrates through membrane holes in a steam form to enter a cold side, and non-volatile components are intercepted on a hot side of the hydrophobic membrane, so that the aim of separating or purifying a mixture is fulfilled. Compared with the traditional thermal desalination process, the membrane distillation technology does not need to heat the feed liquid to the boiling point, only needs to maintain proper temperature difference at two sides of the membrane, can utilize low-grade waste heat, solar energy and other cheap energy sources, obviously reduces energy consumption and can better prevent scaling. Compared with the reverse osmosis technology, the membrane distillation process is almost carried out under normal pressure, the equipment is simple, the operation is convenient, and the membrane distillation process is one of the most promising seawater desalination and sewage and wastewater advanced treatment processes in the 21 st century. In addition, the membrane distillation has strong treatment and recovery capacity on the strong brine, is the only desalination method which can separate out easily-crystallized substances contained in the strong brine through concentration and crystallization, is obviously superior to the reverse osmosis technology, has important significance on the recycling of resources, and can effectively solve the pollution load caused by the discharge of concentrated liquid to the water environment; meanwhile, the membrane distillation product has good water quality, is the method with the highest retention rate in the existing membrane method desalination technology, has the retention rate of 100 percent under the condition that the membrane is not soaked, and has huge commercial potential in the field of ultrapure water preparation. However, membrane fouling, especially salt crystallization fouling, is a major obstacle that hinders the popularization and application of membrane distillation technology at present.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a radioactive wastewater treatment system combining three-dimensional electrocatalysis-conductive film distillation technology, aiming at the defects in the prior art, the removal rate of radioactive elements such as cobalt (Co), uranium (U) and the like in radioactive wastewater reaches more than 99.5, the removal rate of metal ions such as Ca, Mn, Na, Cd and the like reaches more than 99.9%, the high purification of water quality is realized, and the near zero emission treatment, high efficiency reduction and energy consumption reduction of the radioactive wastewater are realized.

The technical scheme is as follows: the radioactive wastewater treatment system based on three-dimensional electro-catalytic conductive membrane distillation comprises a waste liquid storage pool, a sedimentation pool, a membrane distillation heating pool, a three-dimensional electro-catalytic conductive membrane distillation reaction pool and a clear water pool, wherein the waste liquid storage pool is used for placing radioactive waste liquid, the sedimentation pool is used for carrying out precipitation reaction on radioactive elements in the waste liquid and a chemical precipitator, the membrane distillation heating pool is used for heating the waste liquid pretreated by the sedimentation pool, the three-dimensional electro-catalytic conductive membrane distillation reaction pool is used for discharging the radioactive elements in the waste liquid through flocculation and precipitation and intercepting metal ions and radioactive substances, and the clear water pool is used for storing penetrating fluid; also comprises a pH adjusting tank for providing acidic conditions for the sedimentation tank.

Preferably, an electrocatalytic oxidation anode, an iron-carbon micro-electrolysis filler and a conductive distillation membrane are sequentially arranged in a shell of the three-dimensional electrocatalytic conductive membrane distillation reaction tank, hot waste liquid of the membrane distillation heating tank is conveyed into the three-dimensional electrocatalytic conductive membrane distillation reaction tank through a fourth sewage pump, and the waste liquid flows back to the sedimentation tank through a first circulating pump; and (3) conveying the penetrating fluid outlet water of the three-dimensional electrocatalytic conductive membrane distillation reaction tank into a condenser through a second circulating pump for cooling and condensing treatment, and conveying the condensed penetrating fluid into a clean water tank.

Preferably, the temperature of the condenser is controlled at 15 +/-5 ℃; a liquid level controller is arranged in the clean water tank, and clean water exceeding a set water level in the clean water tank is conveyed to a clean water storage tank through a cold side water pump to be stored for later use; and a water outlet quality control system is arranged in the clean water tank and is connected with a computer to control the regeneration of the iron-carbon micro-electrolysis filler in the three-dimensional electro-catalytic conductive membrane distillation reaction tank, the membrane cleaning of the conductive distillation membrane and the membrane replacement.

Further, the iron-carbon micro-electrolysis filler is modified by the carbon nano tube and comprises the following steps:

step 1, pretreatment of a preparation material: putting magnet powder, coconut shell charcoal powder and carbon nanotube powder into 1.5g/LNaOH solution, mixing for 20-30min, taking out, cleaning with ultrapure water, soaking in dilute sulfuric acid solution for 20min, taking out, cleaning, and drying in a 120 deg.C drying oven for 10-12 h;

step 2, preparing filler slurry: weighing 60g of pretreated magnet powder, 30g of coconut shell charcoal powder and 30g of carbon nanotube powder, weighing 5g of bentonite as an adhesive, weighing 5-6g of ammonium oxalate as a pore-forming agent, weighing 3.5g of nickel powder as an additive, placing the mixture into 300mL of ultrapure water, and stirring the mixture for 1-2 hours at 60 ℃ in a water bath to obtain filler slurry;

and 3, granulating the filler: carrying out artificial granulation on the prepared filler slurry, setting the particle size to be 1-2cm, and drying the filler slurry for 3-4h at 150 ℃ in a vacuum drying oven after the granulation is finished;

and 4, insulating treatment of filler particles: performing insulation treatment on the granulated filler particles by using polyimide, and coating a polyimide insulation layer on the surfaces of the filler particles;

step 5, roasting and curing: and (3) placing the filler particles subjected to insulation treatment in a crucible, wrapping the filler particles by using tin foil paper, placing the filler particles in a muffle furnace for roasting at the high temperature of 200 ℃ for 6 hours, and placing the muffle furnace at room temperature for cooling to obtain the self-made carbon nano tube modified iron-carbon micro-electrolysis filler.

Further, the conductive distillation film adopts TiO₂A/CNTs distillation membrane, comprising the steps of:

step 1, pretreating carbon nanotube CNTs powder: weighing 40-50g of CNTs powder, placing the CNTs powder in a beaker, adding 250mL of 200-250mL of deionized water, placing the beaker in a constant-temperature water bath kettle, heating the beaker for 2-3h at 100 ℃, placing the beaker in a room-temperature environment, cooling the beaker, repeatedly washing the beaker with deionized water to remove impurities in the CNTs slurry, performing suction filtration on the slurry by using a vacuum pump to obtain pure CNTs powder, and placing the CNTs powder in a muffle furnace, heating and activating the CNTs powder for 10-12h at 200 ℃;

step 2, preparing nano titanium dioxide/carbon nano tube catalystThe agent material is as follows: weighing 60-70g of tetrabutyl titanate and 20-30g of CNTs powder, adding 100-150mL of anhydrous ethanol, mixing, and magnetically stirring for 50min to form a mixed solution A; weighing 20mL of absolute ethyl alcohol, 50mL of deionized water and 30mL of concentrated nitric acid, mixing, and magnetically stirring for 50min to form a mixed solution B; slowly dropwise adding the solution B into the solution A, standing for 3-6h to form a gel substance, drying in an oven at 120 ℃ for 12h to obtain black-gray powdery particles, grinding the particles into powder by using a mortar, and calcining at 600 ℃ in a muffle furnace for 3h to obtain TiO₂CNTs catalyst powder;

step 3, TiO₂Preparation of a/CNTs distillation membrane: weighing 30-40g of TiO₂Adding the/CNTs catalyst powder into 200mL of ethanol solution, fully mixing, and adding 3-4g of carbon nanotube dispersing agent; after ultrasonic dispersion for 20-30min, adding 5 mass percent of cross-linking agent polyvinylidene fluoride (PVDF), placing in a water bath environment at 65 ℃ for water bath stirring for 1-2h, and obtaining TiO after vacuum deaeration for 20-30min₂CNTs catalyst slurry; adding TiO into the mixture₂Transferring the/CNTs catalyst coating slurry into a material pouring device, taking polytetrafluoroethylene PTFE as a hydrophobic base membrane, placing the hydrophobic base membrane on a coating machine, setting the thickness of a conductive coating to be 200-400 mu m, and using the coating machine to coat TiO₂/CNTs catalyst coating slurry is evenly coated on a PTFE hydrophobic surface, is kept stand and cured for 25min at room temperature and then is placed in a vacuum drying oven for drying for 48h at the temperature of 60-65 ℃, and then TiO is prepared₂/CNTs distillation membrane.

Preferably, the electrocatalytic anode is an iron-aluminum electrode.

Preferably, the conductive distillation membrane has a membrane pore size of 0.1 to 0.4 μm.

Preferably, the bottom of the sedimentation tank is provided with a mud scraper and a mud discharge pipe, the mud scraper is used for periodically scraping chemical sludge deposited at the bottom of the sedimentation tank, the chemical sludge is transported to the outside of the sedimentation tank through the mud discharge pipe and a mud discharge pump, the mud discharge period is controlled by a computer and is set to be 24 hours, and the chemical sludge discharged from the sedimentation tank is subjected to dehydration treatment through freezing-melting-vacuum filtration treatment processes and then is solidified by using cement;

a pH on-line monitoring system is arranged in the sedimentation tank and is used for controlling the extraction of a pH adjusting buffer solution in the pH adjusting tank and the addition of the pH adjusting buffer solution into the sedimentation tank so as to adjust the pH value of wastewater in the sedimentation tank;

controlling the water temperature of the sedimentation tank at 35 +/-5 ℃, setting the pH value to be 2-5, and keeping the sedimentation tank for 1-2 h;

a micropore aeration device is arranged in the sedimentation tank and is used for full contact reaction of a chemical precipitator in the sedimentation tank and radioactive elements in the waste liquid, the aeration intensity of the micropore aeration device is controlled by an air pump, a rotor flow meter monitors the aeration quantity value in real time, the aeration period is controlled by a computer, the aeration period is set to 10 hours, and the single aeration time is set to 30-40 min;

the dosing barrel is communicated with the interior of the sedimentation tank through a second dosing pump and provides chemical precipitation agents for the sedimentation tank.

Preferably, the dosing barrel is used for storing a chemical precipitation medicament prepared by mixing a copper ferrocyanide precipitator and a zinc potassium ferrocyanide adsorbent in proportion, the medicament in the dosing barrel is periodically dosed into the sedimentation tank through a second dosing pump, the dosing period and the dosing amount of the medicament are controlled by the computer, and the dosing period is set to 10 hours.

Preferably, the heat collector heats for membrane distillation heating bath, and the heat collector is connected with the solar energy absorbing device who provides heat energy, is equipped with temperature sensor temperature control in the membrane distillation heating bath and controls at 65 +/-5 ℃.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

according to the invention, radioactive wastewater is pretreated by using a chemical precipitation method, radioactive substances in the wastewater are efficiently removed, radioactive elements are discharged from a liquid phase in the form of chemical precipitation sludge, and are further oxidized, flocculated and intercepted in the wastewater through a three-dimensional electrocatalytic oxidation conductive membrane distillation process, so that the metal ions and the radioactive elements in the radioactive wastewater are efficiently intercepted and removed, the effluent quality is highly purified, the efficient reduction and near zero emission treatment of the radioactive wastewater are realized, and the problem of secondary pollution to the environment caused by the discharge of a membrane filtration concentrated solution is avoided; meanwhile, the radioactive substances in the waste liquid are efficiently transferred from the liquid phase to the solid phase in the chemical precipitation pretreatment and three-dimensional electrocatalytic oxidation conductive membrane distillation treatment processes, so that the storage space of radioactive waste water is effectively reduced; tong (Chinese character of 'tong')The reaction conditions are controlled in the most suitable range by a liquid level controller, a temperature sensor, a pH online control system, a chemical agent online feeding system, a micropore aeration system and a real-time mud scraping system, so that the removal effect of radioactive elements and metal ions is further improved, meanwhile, the full-automatic control of the whole process is realized, and a large amount of manpower is saved. The system has the advantages of novel structure, small occupied area and convenient maintenance, and saves the operation cost by utilizing the clean energy of solar energy. According to the three-dimensional electrocatalytic oxidation system, iron and aluminum are used as the anode and can react with radioactive elements to form flocculating substances, and meanwhile, the self-made three-dimensional filler electrode is utilized, so that the short-circuit current between particle electrodes is efficiently reduced, and the electrode efficiency in the electrocatalytic oxidation process is improved; self-made TiO₂The application of the CNTs conductive distillation membrane can effectively improve the conductivity of the conductive distillation membrane and the yield of active free radicals, and realize the self-cleaning function of the distillation membrane. Chemical precipitation agent, improved three-dimensional electrocatalytic oxidation system and TiO₂The introduction of the/CNTs distillation membrane can remove radioactive elements in the waste liquid through efficient precipitation, effectively relieve the membrane pollution tendency of the distillation membrane, prolong the service life of the distillation membrane and reduce the operation cost caused by membrane cleaning/membrane replacement.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention;

FIG. 2 is a structural diagram of a distillation reaction tank of a three-dimensional electrocatalytic conductive membrane in the invention;

FIG. 3 is a cross-sectional view of a distillation reaction tank for a three-dimensional electrocatalytic conductive membrane according to the present invention;

in the figure: a waste liquid storage tank 1, a sedimentation tank 2, a membrane distillation heating tank 3, a three-dimensional electro-catalytic conductive membrane distillation reaction tank 4, an electro-catalytic oxidation anode 4-1, an iron-carbon micro-electrolysis filler 4-2, a conductive distillation membrane 4-3, a shell 4-4, a reaction tank hot waste liquid water inlet 4-5, a reaction tank hot waste liquid return port 4-6, a membrane component penetrating liquid water outlet 4-7, a clean water tank 5, a condenser 6, a clean water storage tank 7, a first sewage pump 8, a second sewage pump 9, a medicine adding barrel 10, a second feeding pump 11, a pH adjusting tank 12, an acid liquid tank 12-1, an alkali liquid tank 12-2, a first gate valve 13, a second gate valve 14, a first feeding pump 15, a pH signal control system 16, a pH sensor 17, a mud scraper 18, a mud discharge pipe 19, a mud discharge pump 20, a micro-pore aeration device 21, a rotor flowmeter 22, a sludge pump, the system comprises an air pump 23, a third sewage pump 24, a temperature sensor 25, a heat collector 26, a solar energy absorption device 27, a first circulating pump 28, a fourth sewage pump 29, a second circulating pump 30, a cold-side water pump 31, an effluent quality online monitoring system 32 and a computer 33.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

As shown in FIG. 1, the process of the present invention is as follows:

(1) pre-storing waste liquid: and conveying the radioactive waste liquid to a waste liquid storage pool by using a first sewage pump for temporary storage.

(2) Adjusting the pH value in the sedimentation tank: the pH value of the waste liquid in the sedimentation tank is monitored in real time by utilizing a pH online monitoring system, and the opening and closing of the first feeding pump, the first gate valve and the second gate valve are controlled by a computer program, so that the pH value in the sedimentation tank is adjusted within the range of 2-5, and the precipitation reaction of radioactive elements and a chemical precipitator in the waste liquid under an acidic condition is realized.

(3) Adding chemical agents: and (3) preparing a copper ferrocyanide precipitator with a proper concentration and a zinc potassium ferrocyanide adsorbent in advance, mixing the copper ferrocyanide precipitator and the zinc potassium ferrocyanide adsorbent in proportion, storing the mixture in a dosing barrel, controlling the opening and closing of a second dosing pump through a computer program, and setting the dosing period of the chemical agent to be 10 hours.

(4) Aeration treatment in a sedimentation tank: in order to promote the full contact reaction of radioactive substances and chemical precipitants in the sedimentation tank, the opening and closing of an air pump and the flow of the air pump are controlled by a computer program, a microporous aeration device in the sedimentation tank is arranged for periodic aeration, the aeration period is set to be 10 hours, the single aeration time is 30-40min, and a rotor flow meter monitors the aeration amount in real time.

(5) Sludge scraping at the bottom of the sedimentation tank: the opening and closing of the mud scraper in the sedimentation tank are controlled by a computer program, the mud discharging period is set to be 24 hours, chemical precipitated mud scraped by the mud scraper is conveyed to the outside of the sedimentation tank through a mud discharging pipe and a mud discharging pump, the subsequent freezing-melting-vacuum filtration dehydration treatment is carried out, and the solidification treatment is carried out by utilizing cement.

(6) Chemical precipitation pretreatment: introducing the radioactive wastewater in the waste liquid storage tank into a sedimentation tank for pre-sedimentation treatment, fully contacting and reacting the radioactive elements in the waste liquid with a chemical precipitator to generate precipitates, and removing the radioactive substances in the waste liquid from the waste liquid in the form of chemical precipitation sludge, wherein the pre-treatment time of the sedimentation tank is 1-2 h.

(7) Heating wastewater: and conveying the waste liquid pretreated by the sedimentation tank into a membrane distillation heating tank for heating treatment.

(8) And (3) separating the three-dimensional electrocatalytic oxidation conductive membrane by a distillation membrane: after heating treatment, introducing the pretreated waste liquid into a three-dimensional electrocatalytic oxidation membrane distillation reaction tank by a fourth sewage pump, discharging radioactive elements in the waste liquid through flocculation and precipitation in the three-dimensional electrocatalytic oxidation process, efficiently intercepting metal ions and radioactive substances in the waste liquid based on a membrane distillation separation process, and simultaneously slowing down the pollution/membrane wetting of a distillation membrane; and water vapor in the hot waste liquid enters the membrane distillation permeation side through the distillation membrane holes, is condensed into liquid water through the second circulating pump and the condenser, and is temporarily stored in the clean water tank.

(9) Preparing an iron-carbon micro-electrolysis filler: the self-made carbon nano tube modified iron-carbon micro-electrolysis filler comprises the following steps:

step 1, pretreatment of a preparation material: putting magnet powder, coconut shell charcoal powder and carbon nanotube powder into 1.5g/LNaOH solution, mixing for 20-30min, taking out, cleaning with ultrapure water, soaking in dilute sulfuric acid solution for 20min, taking out, cleaning, and drying in a 120 deg.C drying oven for 10-12 h;

step 2, preparing filler slurry: weighing 60g of pretreated magnet powder, 30g of coconut shell charcoal powder and 30g of carbon nanotube powder, weighing 5g of bentonite as an adhesive, weighing 5-6g of ammonium oxalate as a pore-forming agent, weighing 3.5g of nickel powder as an additive, placing the mixture into 300mL of ultrapure water, and stirring the mixture for 1-2 hours at 60 ℃ in a water bath to obtain filler slurry;

and 3, granulating the filler: carrying out artificial granulation on the prepared filler slurry, setting the particle size to be 1-2cm, and drying the filler slurry for 3-4h at 150 ℃ in a vacuum drying oven after the granulation is finished;

and 4, insulating treatment of filler particles: performing insulation treatment on the granulated filler particles by using polyimide, and coating a polyimide insulation layer on the surfaces of the filler particles;

step 5, roasting and curing: and (3) placing the filler particles subjected to insulation treatment in a crucible, wrapping the filler particles by using tin foil paper, placing the filler particles in a muffle furnace for roasting at the high temperature of 200 ℃ for 6 hours, and placing the muffle furnace at room temperature for cooling to obtain the self-made carbon nano tube modified iron-carbon micro-electrolysis filler.

(10) Preparing a conductive distillation film: by using self-made TiO₂A/CNTs distillation membrane, comprising the steps of:

step 1, pretreating carbon nanotube CNTs powder: weighing 40-50g of CNTs powder, placing the CNTs powder in a beaker, adding 250mL of 200-250mL of deionized water, placing the beaker in a constant-temperature water bath kettle, heating the beaker for 2-3h at 100 ℃, placing the beaker in a room-temperature environment, cooling the beaker, repeatedly washing the beaker with deionized water to remove impurities in the CNTs slurry, performing suction filtration on the slurry by using a vacuum pump to obtain pure CNTs powder, and placing the CNTs powder in a muffle furnace, heating and activating the CNTs powder for 10-12h at 200 ℃;

step 2, preparing nano titanium dioxide/carbon nano Tube (TiO)₂/CNTs) catalyst material: weighing 60-70g of tetrabutyl titanate and 20-30g of CNTs powder, adding 100-150mL of anhydrous ethanol, mixing, and magnetically stirring for 50min to form a mixed solution A; weighing 20mL of absolute ethyl alcohol, 50mL of deionized water and 30mL of concentrated nitric acid, mixing, and magnetically stirring for 50min to form a mixed solution B; slowly dropwise adding the solution B into the solution A, standing for 3-6h to form a gel substance, drying in an oven at 120 ℃ for 12h to obtain black-gray powdery particles, grinding the particles into powder by using a mortar, and calcining at 600 ℃ in a muffle furnace for 3h to obtain TiO₂CNTs catalyst powder;

step 3, TiO₂Preparation of a/CNTs distillation membrane: weighing 30-40g of TiO₂the/CNTs catalyst powder is added into 200mL of ethanol solution, and after full mixing, 3-4g of carbon nano tube dispersant is added. After ultrasonic dispersion for 20-30min, adding 5 mass percent of cross-linking agent polyvinylidene fluoride (PVDF), placing in a water bath environment at 65 ℃ for water bath stirring for 1-2h, and obtaining TiO after vacuum deaeration for 20-30min₂CNTs catalyst slurry; adding TiO into the mixture₂Transferring the/CNTs catalyst coating slurry into a material pouring device, taking Polytetrafluoroethylene (PTFE) as a hydrophobic base membrane, placing the base membrane on a coating machine, and arranging a conductive coatingThe thickness is 200-400 mu m, and TiO is coated by a film coating machine₂/CNTs catalyst coating slurry is evenly coated on a PTFE hydrophobic surface, is kept stand and cured for 25min at room temperature and then is placed in a vacuum drying oven for drying for 48h at the temperature of 60-65 ℃, and then TiO is prepared₂/CNTs distillation membrane.

Wherein, the temperature of the membrane distillation heating pool is controlled to be 65 +/-5 ℃; controlling the water temperature of the sedimentation tank at 35 +/-5 ℃, setting the pH value to be 2-5, and keeping the sedimentation tank for 1-2 h; a liquid level controller, a pH online control system, a temperature sensor, a chemical precipitation agent online feeding system, an online mud scraping system and an aeration device online control system are arranged in the sedimentation tank; the temperature sensor is arranged in the membrane distillation heating pool, and the heat collector in the membrane distillation heating pool is connected to the solar absorption device, so that the recycling of clean energy is realized, the energy consumption is obviously reduced, and the operation cost is saved; a water quality on-line monitoring system and a liquid level controller are arranged in the clean water tank, and the regeneration period of the iron-carbon micro-electrolysis filler in the three-dimensional electro-catalytic conductive membrane distillation reaction tank and the membrane cleaning and membrane replacement frequency of the conductive distillation membrane are controlled by a computer; the membrane aperture of the membrane component is 0.1-0.4 μm, and a PTFE membrane with higher hydrophobicity is selected as a substrate material; the temperature of the penetrating fluid cooling device is controlled at 15 +/-5 ℃.

Example 1

As shown in fig. 1 and 2, a radioactive wastewater treatment system combining three-dimensional electrocatalysis-conductive membrane distillation technology comprises a waste liquid storage tank 1, a pH adjusting tank 12, a sedimentation tank 2, a membrane distillation heating tank 3, a three-dimensional electrocatalysis-conductive membrane distillation reaction tank 4, a condenser 6 and a clean water tank 5 which are connected in sequence; a second sewage pump 9 is arranged on a connecting pipeline between the waste liquid storage tank 1 and the sedimentation tank 2, the membrane distillation heating tank 3 and the three-dimensional electrocatalytic conductive membrane distillation reaction tank 4 are connected through a pipeline to form a first circulating system, a third sewage pump 24, a fourth sewage pump 29 and a first circulating pump 28 are arranged on the connecting pipeline of the first circulating system, the three-dimensional electrocatalytic conductive membrane distillation reaction tank 4 and the clean water tank 5 are connected through a pipeline to form a second circulating system, and a condenser 6 and a second circulating pump 30 are respectively arranged on the connecting pipeline of the second circulating system; the sedimentation tank 2 is connected with a pH adjusting tank 12, and a first feeding pump 15, a first gate valve 13 and a second gate valve 14 are arranged on a connecting pipeline of the sedimentation tank 2; the sedimentation tank 2 is connected with a dosing barrel 10, and a second dosing pump 11 is arranged on a connecting pipeline of the sedimentation tank 2; the first feeding pump 15, the first gate valve 13, the second gate valve 14 and the second feeding pump 11 are connected under the control of a computer 33. The sedimentation tank 2 consists of a dosing barrel 10, a pH sensor 17, a pH signal control system 16, a mud scraper 18, a mud discharge pipe 19, a mud discharge pump 20, a microporous aeration device 21, a rotor flow meter 22 and an air pump 23.

Firstly, the radioactive waste liquid is conveyed to the waste liquid storage tank 1 by the first sewage pump 8 for temporary storage. The waste water stored in the waste liquid storage tank 1 is transported to the sedimentation tank 2 through a second sewage pump 9 for pretreatment. The chemical precipitation agent 10 is added, the sludge scraping device 18 is opened and closed, and the microporous aeration device 21 is opened and closed under the control of a computer program.

Before operation, enough acid liquid 30% hydrochloric acid and alkali liquid 30% sodium hydroxide are prepared and stored in an acid liquid pool 12-1 and an alkali liquid pool 12-2 of a pH adjusting pool 12 respectively, and then according to a pH on-line monitoring sensor 17 and a pH signal control system 16 in a sedimentation pool 2, opening and closing of a first feeding pump 15, a first gate valve 13 and a second gate valve 14 are controlled through a computer program, and the pH of radioactive waste liquid in the sedimentation pool 2 is adjusted to be within a range of 2-5. When the pH on-line monitoring sensor 17 shows that the pH value of the waste liquid in the tank is higher than 5, the computer program controls the first feeding pump 15, the first gate valve 13 and the second gate valve 14 to be opened, and absorbs the acid liquid from the acid liquid tank 12-1 of the pH adjusting tank 12 to adjust the pH value to be within the range of 2-5, and then the computer program controls the first gate valve 13 and the first feeding pump 15 to be closed.

The method comprises the steps of preparing enough mixed liquor of 20% of copper ferrocyanide precipitator and 5% of zinc potassium ferrocyanide adsorbent in advance, placing the mixed liquor in a dosing barrel 10, controlling the second dosing pump 11 to be periodically opened and closed through a computer program, and conveying chemical agents into a sedimentation tank 2, wherein the dosing period is set to 10 hours.

After the pH value of the waste liquid in the sedimentation tank is adjusted, the opening of the microporous aeration device 21 and the air pump 23 is controlled by a computer program, the microporous aeration device 21 and the air pump 23 are controlled by the computer program to be closed after aeration is carried out for 30-40min, and the aeration period is set to be 10 h; after the aeration is finished, the chemical precipitation reagent in the sedimentation tank 2 and the radioactive elements in the waste liquid form precipitates which are gradually settled to the bottom of the sedimentation tank 2; the chemical sludge deposited at the bottom is periodically scraped by the sludge scraping device 18 at the bottom of the sedimentation tank 2 and is transported to the outside of the sedimentation tank 2 through the sludge discharge pipe 19 and the sludge discharge pipe 20, the sludge discharge period of the sludge scraping device is controlled by a computer program to be 24 hours, and the chemical sludge discharged from the sedimentation tank 2 is dehydrated through the freezing-melting-vacuum filtration treatment process and then is solidified by using cement.

After the chemical precipitation pretreatment is finished, the supernatant liquid pretreated in the sedimentation tank 2 is introduced into the membrane distillation heating tank 3 by a third sewage pump 24 for heating treatment. The heat in the heating pool 3 is provided by solar energy, and the solar energy absorption device 27, the heat collector 26 and the temperature sensor 25 in the pool are connected, so that the purpose of heating the waste liquid is achieved. The embodiment adopts the temperature difference control heat collection principle, after the solar heat source absorption device 27 absorbs solar radiation, the temperature of the heat collection tube rises, and when the temperature difference set value between the heat collector 26 and the membrane distillation heating pool 3 is reached, the monitoring system sends out an instruction, cold water in the central water heater is input into the heat collector 26, and the water returns to the membrane distillation heating pool 3 after being heated, so that the temperature of waste liquid in the pool reaches the set temperature, and the water temperature in the membrane distillation heating pool 3 is controlled to be 65 +/-5 ℃.

According to the temperature sensor 25 in the membrane distillation heating pool 3, after the temperature of the waste liquid in the pool reaches a set temperature range of 65 +/-5 ℃, starting the fourth sewage pump 29, conveying the hot waste liquid in the membrane distillation heating pool 3 to the three-dimensional electro-catalytic conductive membrane distillation reaction pool 4, further intercepting and removing radioactive elements and metal ions in the waste liquid, as shown in fig. 3, conveying the hot waste liquid from a hot waste liquid inlet 4-5 of the reaction pool to the hot side of the reaction pool 4, and returning the hot waste liquid from a hot waste liquid return port 4-6 of the reaction pool to the sedimentation pool 2 by the first circulating pump 28; an electrocatalytic oxidation anode 4-1 of the three-dimensional electrocatalytic electrode and an iron-carbon micro-electrolysis filler 4-2 perform catalytic oxidation treatment on radioactive elements in the waste liquid, so that the radioactive substances in the waste liquid form flocculent precipitates to be intercepted by a distillation film 4-3, and meanwhile, the iron-carbon micro-electrolysis filler 4-2 performs adsorption-solidification treatment on the radioactive elements in the waste liquid; TiO 2₂the/CNTs conductive distillation membrane 4-3 further performs adsorption-interception treatment on radioactive substances in the waste liquid, and TiO₂The catalysis of the/CNTs conductive distillation membrane 4-3 can realize the self-cleaning function of membrane surface pollutants and slow down the pollution/membrane wetting tendency of the distillation membrane; low-temperature clean water in the clean water tank 5 is conveyed to the cold side of the conductive distillation membrane 4-3, penetrating fluid generated in the wastewater treatment process flows back to the clean water tank 5 after being condensed by a second circulating pump 30 and a condenser 6 from a penetrating fluid water outlet 4-7 of the membrane module along with the low-temperature clean water, and the temperature of the condenser 6 is controlled to be 15 +/-5 ℃; in the embodiment, a hydrophobic PTFE film with the aperture of 0.1-0.4 mu m is selected as a base film to prepare excellent TiO₂the/CNTs conductive distillation membrane 4-3.

In order to control the reduction and treatment effects of the three-dimensional electrocatalysis-conductive film distillation reactor combined process on radioactive wastewater in an optimal range, a liquid level control system, a temperature sensor, a pH online control system, a chemical precipitant online feeding system, a micropore aeration system and a real-time mud scraping system are arranged in a sedimentation tank 2, a temperature sensor is arranged in a film distillation heating tank 3, an effluent water quality online monitoring system 32 is arranged in a clean water tank 5, water quality data are transmitted to a computer 33 in real time, the regeneration period of iron-carbon micro-electrolysis fillers 4-2 in a three-dimensional electrocatalysis conductive film distillation reaction tank 4 and the film cleaning and film replacement frequency of conductive distillation films 4-3 are controlled by the computer 33 according to the monitoring data of the effluent water quality online monitoring system 32, the full-automatic control of the whole process is realized, and a large amount of manpower is saved.

Example 2

The device and the process are adopted to treat the medium-level radioactive wastewater generated by a certain nuclear power station.

(1) Introducing the medium level radioactive wastewater generated by the nuclear power station into a sedimentation tank 2 for chemical sedimentation pretreatment, adjusting the pH of the waste liquid in the tank to be about 3, and controlling the water temperature to be about 35 ℃;

(2) aerating in the sedimentation tank 2 for 30min, standing for sedimentation for 60min, introducing the supernatant in the sedimentation tank 2 into the membrane distillation heating tank 3 for heating treatment after sedimentation, and controlling the water temperature to be about 65 ℃;

(3) after the temperature of the waste liquid in the membrane distillation heating tank 3 rises to 65 ℃, the hot waste liquid is conveyed to the three-dimensional electro-catalytic conductive membrane distillation reaction tank 4 through a fourth sewage pump 29 for further adsorption-flocculation-interception treatment;

(4) the hot side of the three-dimensional electrocatalysis conductive membrane distillation reaction tank 4 and the sedimentation tank 2 form a circulating system through a first circulating pump 28 and a fourth sewage pump 29; permeating water vapor on the cold side is condensed by a second circulating pump 30 and a condenser 6 and then is conveyed into a clean water tank 5, and the temperature of the condenser 6 is controlled to be about 15 ℃; TiO in the reaction tank 4₂the/CNTs conductive distillation membrane 4-3 adopts a hydrophobic PTFE membrane with a pore diameter of 0.22 μm as a base membrane.

Operating according to the above method, the radioactive waste liquid produced by the nuclear power station has a total activity of about 7X 10⁶Bq/L, detected to contain Co²⁺、Ca²⁺、Mn²⁺、Na⁺、Cd²⁺、UO₂ ²⁺、Sr²⁺、Ba²⁺Plasma with initial pH value of about 2.0, purifying the Co of the effluent after the treatment of the three-dimensional electrocatalysis-conductive film distillation reactor technology combination process²⁺The removal rate reaches 99.6 percent, and UO₂ ²⁺The removal rate reaches 99.8 percent, and Ca is added²⁺The removal rate reaches 99.9 percent, and Na⁺The removal rate reaches 99.9 percent, and Mn is removed²⁺The removal rate reaches 99.9 percent, Sr²⁺The removal rate reaches 99.5 percent, and Ba is added²⁺The removal rate reaches 99.4 percent, and the total activity of the radioactivity of the effluent<1Bq/L, meets the relevant requirements of the national comprehensive sewage discharge standard GB 8978-.

The embodiments of the present invention are not described in detail, but are known in the art, and can be implemented by referring to the known techniques.